Enzymes: Mechanism of action
How does enzyme work?
Enzymes are biomolecules and they speed up reactions by decreasing the rate of a chemical reaction. Enzymes will not alter reaction equilibrium but decrease rate of the chemical reaction by decreasing the free energy of activation. To know more please watch the below-embedded video.
Mechanism of enzyme action
There are two theories or models or hypotheses for the mechanism of enzyme action. The first theory proposed by Emil Fisher, known as lock and key model or rigid template model or Fisher model and the second one is the induced fit model or hand-in-glove model or Koshland model proposed by Daniel E Koshland.
The active site of an enzyme
It is a region where the substrate binds during enzymatic reaction. It has got two sites namely biding site and catalytic site. An enzyme is a macromolecule, it is a big molecule when compared to the substrate. So, within an enzyme there is a small area or region, that is called an active site of an enzyme. So, this small area looks like a cavity with the X-Ray diffraction study. Please watch below embedded video to know more about the active site of an enzyme.
Cofactors and Coenzymes
If you take enzyme, it is a protein, almost all enzymes are proteins except ribozyme and this protein part of the enzyme is called apoenzyme. Several enzymes apart from being a protein, also possess a non-protein component. So, such nonprotein components are called cofactors. So, cofactors are non-protein components. So, this non-protein component of enzyme, we can call it as prosthetic groups. So, now we have an apoenzyme and we have prosthetic groups. So together apoenzyme and prosthetic group, we can call it as a holoenzyme. So, the prosthetic groups are collectively called as cofactors and these cofactors could be coenzymes or metal ions. Coenzymes are also cofactors even metal ions are also cofactors. Usually, these cofactors enhance enzyme-catalyzed reactions. So, usually, coenzymes are organic components. whereas metal ions are inorganic. To understand further please watch below embedded video.